Sound-recording and sound-reproducing and locating apparatus



Aug. 4, 1931. F. M. DOOLITTLE SOUND RECORDING AND SOUN D REPRODUGING AND LOCATING APPARATUS Filed June 14, 1921 iiw/ww Am 6' Patented Aug. 4, 1931 UNITED STATES PATENT "OFFICE FRANKLIN m. DOOLITTLE, or NEW HAVEN, oonnno'rrcu'r, ASSIGNOR 'ro RADIO CORPORATION or AMERICA, A CORPORATION or DELAWARE soon-RECORDING AND sounn-nnrnonucme AND rocA'rmo APPARATUS Application filed June 14,

The present invention relates to sound, recording, reproducing and locating apparatus and is directed in particular to a sound recording system capable of producing a record which when reproduced will evoke in "the mind of the listener a sense of the motion which occurred at the point from which the sound originates.

A principal object of the present invention is to provide a system andmethod which is capable of translating sounds originating at any selected point into a plurality of re corded impulses, each of which sets of impulses corresponds to time separated records of the same sound as varied in accordance with the time of arrival of the sound from the original source with respect to a pair of fixed predetermined points from which the sound is picked up, may then be reproduced g soas to furnish two separate reproduced versions of the same sound. Thus, when a listener hears the sound thus reproduced, it

is possible for the listener to picture the I movement which occurred at the point from 5 whichthe original sound was translated into a recording.

Still other and further objects of the invention will become apparent and will suggest themselves to those skilled in the art to which the invention relates, by reading the 'following specification and claims in confection with the accompanying drawings wherein:

Fig. 1. A diagrammatic view of one form which a sound-recording, sound-reproducing and locating apparatus embodying my invention may assume.

Fig. 2. A broken detail view partly in elevation and partly in section showing one method of recording two separate versions of the same sounds, this device being also applicable, when reversely used, to simultaneously reproduce these two separatelyrecorded versions of the same sounds.

Fig. 3. A diagrammatic view showing an apparatus for reproducing two versions of the same sounds. Fig. 4. A broken detail view showing the 60 transmitting of two separate versions ot'the 1921. Serial No. 477,360.

same sounds to the ears of a listener by acoustlc means.

Fig. 5. A diagrammatic view showing electrical means for transmitting two separate versions of the same sounds to the ears of the listener.

To the listener to any phonograph as at present made and used, the sounds reproduced by it appear to emanate from a'single point. For illustration, in-the phonographic reproduction of a musical performance, the

listener receives no impression whatever as to the relative location of the respective musi- I cians and their instruments. No matter how many voices or instruments or both are engaged in the performance reproduced, the music appears to proceed from a single point. The same thing is true in the entire range of the use of the phonograph, which distorts the sounds reproduced by it in so far as it eliminates-the question of location. The described peculiarity of sounds reproduced by the phonograph appears to be due to the fact that correct sensations of the location of the emission of sounds depends upon the use of both ears and that this sense of location is measurably impaired, if not destroyed, when one ear only is available. With the end in 'sists in a method of simultaneously producing two separate versions of the same sounds, which versions may difier in phase relation and in thereafter reproducing those separate versions in which the diiierence in time relation has been permanently recorded and conveying them to the respective ears of the listener. My invention further consists in a dupleX-sound-recording instrument for recording two versions of the same sounds, and two sound-receivers leading from the said in- I strument and separated from each other by substantially ears.

My improved apparatus may assume a variety of forms according to the use to be made the separation of the human of it, as, for instance, phonograph recording,

phonograph reproducing, the transmission of mus1c or speeches from one point to an other and the like. My improvement may also be embodied in'a detectaphone, enabling notonly voices to be heard but their relative mayalso be used as an accessory to movingv location to be visualized. My improvement chosen receivers 6- and 7, arranged to operate telephone-transmitters or microphones 8 and 9 which are mounted or installed so as to be separated from each other by a distance corresponding ,to the separation of the ears of the average individual, this particular feature being the main structural characteristic of my invention, insofar as it provides for the permanent recording of two versions differentiated in, time relation of the same sounds, which is the basic concept of my ingvention. The sounds gathered by the receivers 6 and 7 are amplified by amplifying apparatus 10 and 11, and led to telephone receivers 12 and 13 having horns 14 and 15 respectively arranged, in line with sound-receivers 16 and 17 leading to sound-recorders 18 and 19 furnished with needles or points in direct contact with a sound-recording disk 22 of ordinary character, except in so far as it has two continuous spiral grooves running side by side instead of a single groove. By means 'of such an apparatus, two separate versions differentiated in time relation of the same sounds are simultaneously but separately recorded.

When aduplex sound-locating record made in the manner just described is reproduced, as for instance by an apparatus like that shown in Fig. 2, the extraordinary illusion is created in the mind of the listener of the relative position of the instruments or vocalists 01' speakers at the time when the musical performance or speech recorded was going on. The illusion is still further heightened by the additional illusion of the relative movement of any of the musicians, or speakers,.during the making of the record, so that the listener in his minds eye sees the musicians or speakers move about upon the stage or in the room where they are.

In Fig. 3 I have shown a phonograph 23 mounting a record 24 which it is to be assumed, contains two spiral grooves produced as'already described. These spiral grooves respectively receive the needles of the soundrepro'ducers 25 and 26 connected with the acoustically-insulated air-passages 27 and 28 musicians taking part in the performance recorded. I

Of course, it would be possible to connect the two tone-arms 27 and 28 acoustically as shown in Fig. 4, instead of utilizing an electric system of transmission, an illustration of which is shown in Fig. 5, in which the-soundreceivers 39 and 40 of telephone transmitters 41 and 42 are respectively connected by conducting wires 43 and 44 to telephone receivers 45 and 46 joined by a head-band 47.

WVhatever the form of apparatus employedfor recording and reproducing sounds under my invention it is essential that the same.

sounds be recorded by sound receiving means so installed as to receive the sounds in a manner simulating or approximating the reception of sounds by the ears of a person similarly located.

I claim:

1. The method of making p'ermanentrecords of sounds which comprises receiving at two predetermined and separated points sound waves as independent trains of sound energy from the same source, and independently translating the sound energy corresponding to each train of sound energy into a permanent record as two time separated versions of the same'sound in which each of the recorded sound waves co-acts with the other to approximate, when simultaneously reproduced, an effect simulating the'binaural effect which would be produced upon the ears of a person located at a receiving point.

2. The method of sound recording which comprises receiving two time separated independent trains of like sound energy from.

permanent record in which the time separation of the two records of the same sound is varied in accordance with the arrival of sound from the original sound source with respect to a pair of fixed predetermined points so arranged as to simulate the binaural effect which would-be produced upon the ears of a listener similarly positioned. I

3. The method of recording sounds which comprises receiving independent time sep-' arated variations of the same sound at 'two predetermined points, translating the sound energy into variations in electrical energy, reconverting the electrical energy intosound energy, recording the variations in reconverted sound energy upon a permanent recording surface in a plurality 0f-paths each bearing a time separated version of the same produced from the recording surface evokes on the mind of the listener amental picture of substantially the relative position. from which the various sounds originated.

4. A record for reproducing binaural effects upon the ears of listeners which comprises a pair of continuous and adjacent tracks, each of said tracks being a record of independent trains of the same sound energy having a, time separation simulating the separation at which a sound would reach the ears of a listener stationed at the point where the sound was originally received for recording.

5. A: record. for reproducing binaural efii'ect's upon the ears of listeners which comprises a plurality of tracks each bearing a record of independent time separated variations of the same sound, each of said tracks being on the same side of the record and ex- 

